Study Of On-the-Fly Calibration For 2-D Precision Motion Stage

With the extensively application of high precision displacement sensing technology and precision motion stage, people put forward high demand on the stage displacement calibration. Present calibration of motion stage is used to calibrate static stage. In some occasions as the calibration of air-bearing stage, the vibration may cause errors. This thesis presents a calibration method when the stage is in motion. This method can realize the synchronous sampling between the displacement sensing of stage system and the displacement sensing of calibration system. It can reduce the errors caused by vibration when the stage is static and complete on-the-fly calibration to the displacement of high precision motion stage.The high precision motion stage consists of blue-laser interferometric displacement sensor and air-bearing slider. A AQB calibration system is established based on the high precision motion stage, Agilent 5529A laser interferometer and E1735A data acquisition module. The subdivision system is first tested for generating well AQB signals. The AQB signal conditioning circuit is then designed and its PCB is made. Signal conditioning PCB contains following circuit, differential circuit, amplification circuit, filtering circuit, and reverse-phase circuit. Well AQB signals are generated. Once the calibration hardware is ready, on-the-fly calibration software is developed and the executive program is generated under the AQB mode of E1735A.In the course of on-the-fly calibration, the stage is driven by a linear motor under a constant velocity. Blue-laser interferometric displacement sensor of the stage generates analog AQB signals. Digital AQB signals are obtained by signal conditioning PCB and the subdivision system and fed to the Mudulo-counter of E1735A for pulse counting. After initializing with sampling interval, Mudulo-counter outputs a transient puls when the conter is overflow. The transient puls enables a storage of displacement data of calibration system in hardware buffer. By accumulating digital AQB signals, a displacement data of motion stage is obtained. Based on the transient pulses generated from Mudulo-counter, the displacement data from calibration system matches that from motion stage. The experimental results are processed by using linear regression analysis method, and the AQB calibration results is further analyzed.